public ReceiptAttempt ProcessPurchaseAttempt (string username, string password, Item clientDescriptionOfItem) {
return ReceiptAttempt.Make(() => {
Global.DoWrappingExceptions<GildedRoseClientComplaintException>(() => {
username = username.NullHandlingNormalize();
password = password.NullHandlingNormalize();
clientDescriptionOfItem = clientDescriptionOfItem.WithNormalizedStrings();
Assert.NotNull(username);
Assert.NotNull(password);
clientDescriptionOfItem.AssertNotNullAndInvariantsIfAny();
}, "Invalid data.");
lock (model) {//todo find a way to not do this.
var customer = model.AuthenticateOrThrow(username, password);
return model.ConductSaleOrThrow(customer, clientDescriptionOfItem);
}
});
}
public Receipt ConductSaleOrThrow (Customer customer, Item clientDescriptionOfItem) {
var actualItem = ItemMatching(clientDescriptionOfItem);
if (actualItem == null) Global.ThrowComplaint("Item not carried.", true);
if (!customer.CanAfford(actualItem)) Global.ThrowComplaint("Insufficient money.", true);
return ConductSale(customer, actualItem);
}
///<summary>Precondition: sale is valid.</summary>
public Receipt ConductSale (Customer customer, Item item) {
customer.MoneyInWallet -= item.Price;
MoneyInRegister += item.Price;
inventory.Remove(item);
return new Receipt(customer, item);
}
public Item ItemMatching (Item description) {return inventory.ItemMatching(description);}
public void Remove (Item item) {items.Remove(item);}
public Item ItemMatching (Item description) {return items.FirstOrDefault(i => i.InterchangeableWith(description));}
uint price = 10;//Invariant: positive.
public bool InterchangeableWith (Item other) {return name == other.name && description == other.description && price == other.price;}
public bool CanAfford (Item item) {return item.Price <= MoneyInWallet;}
[Theory] public static void Invariants (Item item) {
Assume.That(item != null);
// ReSharper disable once PossibleNullReferenceException
item.AssertInvariants();
}